1. Field of the Invention
This invention relates to a detergent supply pack for use with institutional dishwashing machines. The invention also relates to a process for the production of the supply pack and, more especially, to a process for the production of a supply pack for a solid detergent block for use with institutional dishwashing machines.
2. Statement of Related Art
Hitherto, various products and packs have been developed to provide institutional dishwashing machines with a supply of detergents from which measured amounts of detergent are dispensed to the dishwashing machine. These products include detergents in powder form, in liquid form, and in paste form which are generally packed in dispensers specifically corresponding to the particular product type and which are automatically dispensed on demand. The necessary dispensers are expensive, especially in regard to production and maintenance. More recently, block-form detergents for domestic and institutional dishwashing machines have been developed, which have the advantage of being dimensionally stable. These detergents are dissolved by simply spraying with water, and then are delivered to the wash liquor in solution. Since institutional detergents often have a high caustic alkali content, contact with the skin should be avoided; block-form detergents are much safer to handle and thus also superior in this regard.
U.S. Pat. Nos. 4,569,780 and 4,569,781 (and corresponding published European patent application No. 3,769) describe a detergent container suitable for use in dishwashing machines adapted for molding detergents in block form. A molten detergent is poured into the container and allowed to solidify; the detergent is subsequently dissolved from the container on contact with a stream of aqueous liquid from the dishwasher. The advantage of a block-form detergent of this type is that, with proper handling, contact with the skin is virtually eliminated.
Owing to the shape thereof, however, the container described in these patents requires an unreasonably high consumption of flushing water to remove residual detergent in the container. The incomplete dissolution of detergent residues in the container is frequently so pronounced that a "container empty" signal is triggered, although substantial residues of product are clearly still present. This situation is unacceptable both for economic reasons and for safety reasons. Detergent residues in the container are a potential danger source to the user when the supposedly empty container is being replaced by a completely full container. Further, since the container described in these patents is formed from a stable, thick-walled plastic material and is intended to be thrown away when empty, its use is environmentally unsound.
U.S. Pat. No. 4,426,362 describes a dishwasher distributor for a solid block-form molded detergent. The block-form detergent of this reference is positioned with its casting mold in the receiving means of the distributor so that the casting mold surrounds the detergent block during the flushing-out process and touches it on all sides except for one free face. Once again, contactless handling of the detergent is provided, but once again, the consumption of water is high and complete emptying is not guaranteed.